Left-wing lawyer Giuliano Pisapia triumphed in Milan against Letizia Moratti from Berlusconi's People of Freedom party, ending the right's 18-year hold on the city and dealing a heavy blow to the Italian premier in his home town.

Pisapia garnered 55.10 percent of the vote, while Moratti won 44.89 percent in the second round of a mayoral vote held on Sunday and Monday.

In Naples, which was already controlled by the left, Luigi De Magistris, a former prosecutor, also won out against his rival with 65.37 per cent.

The centre-right lost other votes in Cagliari, Novara and Trieste but the defeat in Milan -- Italy's economic capital -- was seen as the most symbolically significant and a bellwether for anti-Berlusconi sentiment.

"I am delighted! This is an awakening of consciences that have been asleep during years of incivility, of an absence of culture," said Giovanna Cardarelli, 55, in a crowd of thousands rallying in front of Milan cathedral.

Berlusconi had actively campaigned on Moratti's behalf and declared the vote should be seen as a test of his popularity, which has been falling after a series of legal and sex scandals and continued weakness in the economy.

Berlusconi's trial on charges of having sex with an underage prostitute and abuse of power is to resume in Milan on Wednesday, although he will not attend.

Analysts say the defeat will put pressure on the coalition between Berlusconi and the Northern League party, which has shown signs of growing disenchantment with the PrimeMinister's leadership in recent weeks.